Presumption of culpable mental state shifts burden to accused to disprove mens rea; rebuttal requires proof beyond reasonable doubt. The provision places the evidential burden on the accused to prove absence of mens rea, treating culpability to include intention, motive, knowledge, belief and reason to believe; the presumption is rebutted only if the accused proves lack of culpable mental state beyond reasonable doubt, not by mere preponderance of probability.